Star Dust Nova Sheds Light On Galaxy

A blazing new supernova, an exploding star, has given astronomers in the Southern Hemisphere a rare opportunity to analyze the enigmatic dust clouds that shroud a relatively nearby galaxy.

The supernova, a star in the galaxy Centaurus A, was discovered last month by an amateur astronomer in Australia.

Centaurus A is roughly 13 million light-years from Earth, and the supernova astronomers are now observing occurred at about the time man`s earliest hominid ancestors walked the Earth. Astronomers estimate that a supernova explodes in an average galaxy once every 100 years.

Among the major telescopes brought to bear on the object were those operated by the U.S. National Optical Astronomy Observatories, notably the Cerro Tololo Inter-American Observatory in Chile.

Dr. Mark Phillips, an astronomer there, said the supernova was spotted about a week before it flared into maximum brilliance, and scientists thus had ample time to measure the changes it underwent.

A spokesman for the national observatories said that the brightness of the supernova appeared to have reached a peak and would henceforth decline.

The special scientific value of the discovery is the fact that the supernova lies deep within Centaurus A, behind a dense lane of dust that girdles the elliptical galaxy.

Light from the supernova is so intense that it shines through the dust, and by determining the spectrum of light that is absorbed by the dust lanes, scientists can infer their chemical composition.

Astronomers have so far discerned the elements sodium and calcium in the dust.

The absolute brightness of the supernova is assumed to be the same as that of other supernovas of the same class that have been measured in other galaxies.

Astronomers are therefore using the new supernova as a kind of yardstick to determine the distance to Centaurus A with greater precision than was possible before the explosion.